Electric switches



March 27, 1956 A. v. WATERS 2,740,013

ELECTRIC SWITCHES Filed Sept. 8, 1953 Fflfa 681%? United States Patent2,740,013 ELECTRIC SWITCHES Albert Victor Waters, Perivale, Greenford,England, assignor to C. A. V. Limited, London, England ApplicationSeptember 8, 1953, Serial No. 378,740

Claims priority, application Great Britain September 17, 1952 1 Claim.(Cl. 200-413) This invention has for its object to provide in a simpleform, an electric switch of the pull-push type adapted to serve also asan automatic thermally-operable circuitbreaker in the event of anoverload.

A switch in accordance with the invention comprises an axially slidableand manually operable plunger, 21 contact piece carried by the plunger,a thermally-deformable contact component of the kind herein specifiedprovided with a second contact piece, and means carried by the plungerfor re-setting the said component after thermal deformation.

In the accompanying drawings:

Figure l is a sectional side elevation and Figure 2 an end elevation ofa switch embodying the invention.

Figure 3 is a plan of the thermally-deformable contact component.

Referring to the drawings, a hollow body part a having therein acylindrical bore, has slidably mounted in the bore a plunger b which atits outer end is provided with or is shaped to serve as a finger piecec. The on" and off positions of the plunger are determined by a ballcatch or catches d loaded by a spring e and adapted to engage recessesfin the bore of the body part.

At the inner end of the plunger is secured a contact piece g, and thisis connected by a flexible metal strip h to a circuit terminal i carriedby a part i which is secured to one end of the body part a.

The complementary contact piece k is formed on or secured to a flexibleand elastic bi-metal component of the kind which requires to be resetafter thermal deformation, this component being secured to anothercircuit terminal m on the part i of the switch. In one convenient andknown form this component consists of a rectangular piece of bi-metalsheet 11 (Figure 3) which is slotted to provide a tongue a lying betweena pair of side parts, and is slightly bowed as shown in Figure 1, thecontact piece k being formed on or secured to the free end of the Whenheated the tongue and side parts bend relatively to each other inopposite directions, with a flick-action, and so effect separation ofthe contact pieces g, k, the tongue and side parts remaining in thiscondition on cooling.

To etfect re-setting of the tongue and side parts of thetherma1lydeformable component after thermal deformation, and so restorethem to their initial relationship, there is provided on the inner endof the plunger a striker p which on retraction of the plunger bearsagainst the tongue piece and thereby causes the side and tongue parts ofthe component to spring back to their normal relative positions.Preferably the striker p is provided with a rubber or like button qwhich when the tongue piece is being re-set presses against an abutmentr on the tongue piece.

To close the switch, the contact pieces are brought together by inwardmovement of the plunger. So long as the current then flowing through theswitch is within a predetermined amount, the contact piece remains inmutual contact, and to open the switch the plunger is retracted. But inthe event of an overload, the bi-metal component is thermally deformedand separation of the contact pieces is thereby effected automatically.Restoration of the component to its normal condition after cooling iseifected by retraction of the plunger.

By this invention a combined manually operable switch and automaticcircuit breaker is provided in a very simple form.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

An electric push-pull switch which is adapted to serve also an anautomatic thermally-operable circuit-breaker overload, and whichcomprises in combination a body part, an axially slidable and manuallyoperable plunger carried by said body part, a contact piece on saidplunger, a thermall -deformable component of the kind which upon coolingafter thermal deformation retains its deformed condition until subjectedto a resetting operation, a second contact piece on said component,means for supporting said component so that the contact piece on saidplunger can be brought into contact with the contact piece on saidcomponent by axial movement UNITED STATES PATENTS 1,767,709 Smith June24, 1930 2,111,943 Schmidt Mar. 22, 1938 2,257,793 Frank Oct. 7, 19412,300,530 Swingle Nov. 3, 1942 2,520,874 Bean Aug. 29, 1950

